It’s easy, you have three basic  statements:

• JOB: Provides a name (jobname) for the batch.
• EXEC: Provides the name of a program to execute.
• DD: For Data Definition, provides inputs/outputs to the program.

Let’s see a JCL example:

//MYJOB     JOBTES 1
//MYSORT    EXEC PGM=SORT
//SORTIN    DD DISP=SHR,DSN=SUP01.TAB.TEST
//SORTOUT   DD SYSOUT=*
//SYSOUT    DD SYSOUT=*
//SYSIN     DD *
SORT FIELDS=(1,4,CH,A)
/*

Now, try to understand what’s happen here.

• MYJOB is the jobname associates to the workload, here it’s “JOBTES”.
• MYSORT is the stepname, which ask the system to execute a program called “SORT”.
• SORTIN is the program input, here with the DSN (Data Set Name) SUP01.TAB.TEST, and the dataset can be shared (DISP=SHR).
• SORTOUT is the SORT program output.
• SYSOUT specifies to send system output to JES (Job Entrey Subsystem), but it’s also possible to send the outpu to a dataset.
• SYSIN tell the SORT program which fields of the SORTIN data records are to be sorted.

Enough for the moment, JCL is quite hard at beginning !

With Unix we talk about “boot” a system, with z/OS we talk about IPL (Initial Program Load). IPL is a hardware function, not a program run on the system. The IPL function reads 24 bytes from an operator-specified or pre-configured device into memory starting at location zero.

With Unix we talk about “files”, with z/OS we talk about Datasets. Datasets are not unstructured streams of bytes, but rather are organized in various logical record and block structures determined by the DSORG (data set organization), RECFM (record format), and other parameters. Programmers utilize various access methods (such as QSAM or VSAM) in programs reading and writing data sets, their choice depending on given data set organization.

With Unix we have the system configuration data in the /etc, with z/OS we have PARMLIB which control how the system IPLs and how address spaces behave.

With Unix we have the Shell scripts, Awk, Perl,.., with z/OS we have REXX execs and CLISTS.

With Unix we have threads which are supported by the Kernel, with z/OS we have tasks or a service request block (SRB).

With Unix we edit data with Vi, emacs, sed, with z/OS we use ISPF, which is more powerful than you can think..

With Unix we have the ps and kill command, to view processes and kill them, with z/OS we have SDSF who allow to view and terminate a job.

IBM took the opportunity to launch a new product called z/OS Management Facility, which will allow programmers to manage and administrate a mainframe with more ease, on the daily z/OS operation.

z/OS 1.11 and z/OS Management Facility will be available on Septembre 25, 2009